• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.28 no.2
• /
• pp.217-222
• /
• 2010

The geoid is the level surface that closely approximates mean sea level and usually used for the origin of vertical datum. For the computation of geoid, various sources of gravity measurements are used in South Korea and, as a consequence, the geoid models may show different results. however, a limited analysis has been performed due to a lack of controlled data, namely the GPS/Leveling data. Therefore, in this study, the gravimetric geoids are compared with the geodetic geoid which is obtained through the GPS/Leveling procedures. The gravimetric geoids are categorized into geoid from airborne gravimetry, geoid from the terrestrial gravimetry, NGII geoid(geoids published by National Geographic Information Institute) and NORI geoid(geoi published by National Oceanographic Research Institute), respectively. For the analysis, the geometric geoid is obtained at each unified national control point and the difference between geodetic and gravimetric geoid is computed. Also, the geoid height data is gridded on a regular $10{\times}10-km$ grid so that the FFT method can be applied to analyze the geoid height differences in frequency domain. The results show that no significant differences in standard deviation are observed when the geoids from the airborne and terrestrial gravimetry are compared with the geomertric geoid while relatively large difference are shown when NGII geoid and NORI geoid are compared with geometric geoid. Also, NGII geoid and NORI geoid are analyzed in frequency domain and the deviations occurs in long-wavelength domain.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.17 no.4
• /
• pp.567-572
• /
• 2016

Many studies have been performed since the introduction of GPS in Korea. As a result, positioning using GNSS was fully proposed. On the other hand, most of these studies focused on accuracy but analytical studies on the GNSS status and the national GNSS infrastructure of Korea are lacking. In this study, the status of multi-constellation GNSS and National Geographic Information Institute's CORS (Continuous Operating Reference Station) were identified for the benefit and direction of GNSS infrastructure enhancement. As a result, it has been operating Multi-constellation GNSS, such as GPS, GLONASS, Galileo, COMPASS, and QZSS for surveying. In addition, improvement was presented by the number of satellites, precision, PDOP, etc. through the experiment about VRS and RTK using Multi-constellation GNSS. Upgrading the infrastructure for satellite surveying was identified as a priority consideration. In the future, if a Multi-constellation GNSS service is possible in VRS service, the satisfaction of public administration service will improve, which will contribute greatly to the advancement of a surveying infrastructure.

• Proceedings of the KAIS Fall Conference
• /
• 2010.05b
• /
• pp.859-862
• /
• 2010

본 연구는 대전광역시의 응급의료서비스 취약지를 도출하고 취약지역의 보건학적 특성 및 응급의료서비스 취약여부와의 관련성을 분석하여 응급의료 관련 정책의 의사결정에 유용한 기초자료로 제공하기 위한 연구이다. 응급의료서비스 취약지 도출은 Arc GIS의 공간분석 방법 중 가중분석(Cost Weighted distance) 방법으로 응급의료센터로부터의 접근성 분석을 하였으며, 응급의료서비스 취약지의 보건학적 특성 및 응급의료서비스 취약여부와의 관련성은 SPSS 17.0을 이용하여 비모수 t-검정 및 다중회귀분석을 시행하였다. 본 연구의 주요 결과는 다음과 같다. 연구지역의 응급의료기관 분포는 동구와 유성구, 대덕구는 지정된 응급의료센터가 없으나 서구와 중구는 응급의료센터가 2개소 이상 위치하고 있어 응급의료기관 분포가 편중되어 있으며, GIS를 활용하여 응급의료센터와의 접근성 분석을 수행한 결과, 대전광역시 자치구별 전체 면적 대비 응급의료서비스 취약지의 비율이 높은 자치구는 동구가 41.2%로 가장 높았다. GIS를 활용하여 행정동별 응급의료서비스 취약지를 분석한 결과, 대덕구 신탄진동, 동구 대청동과 산내동, 유성구 구즉동과 노은2동, 서구 기성동, 중구 산성동으로 나타났으며, 응급의료서비스 취약지 중 기성동, 대청동이 노인 인구밀도가 높게 나타났다. 응급의료서비스 취약여부에 따른 보건학적 특성별 차이를 분석한 결과, 국민기초생활수급권자, 장애인등록자, 농업인구 비율의 평균은 취약지가 비취약지에 비해 높았으며 통계적으로 유의한 차이를 보였다(p<0.01). 응급의료서비스 취약여부를 종속변수로 하고 지역별 보건학적 특성을 독립변수로 하여 로지스틱 회귀분석을 시행한 결과, 농업인구 비율과 국민기초생활수급권자 비율이 높았으며 이는 통계적으로 유의하여 응급의료서비스 취약여부를 설명할 수 있는 변수인 것으로 나타났다(p<0.01, p<0.05). 이상의 결과를 종합하면 대전광역시 5개 자치구의 행정동 중 응급의료서비스 접근 불평등지역이 도출되었고 이러한 지역은 보건학적 특성 중 농업인구 비율과 국민기초생활수급권자의 비율이 높았으며 이는 통계적으로 유의하여 응급의료서비스 취약여부와 관련성이 있는 것으로 나타났다. 향후 효율적인 응급의료 자원 분배를 위해서는 GIS를 활용한 의사결정이 필요하며, 응급의료서비스 이용의 형평성을 증진시키기 위해서 응급의료서비스의 사각지대에 놓여있는 지역의 보건학적 특성을 고려한 정책이 시행되어야 할 것으로 사료된다.

• Economic and Environmental Geology
• /
• v.47 no.1
• /
• pp.49-59
• /
• 2014

Rainfall-induced landslides are caused by reduction of effective stress and shear strength due to rainfall infiltration. In order to analyze the susceptibility of landslides, the statistical analysis approach has been used widely but this approach has the limitation which cannot take into account of landslide triggering mechanism. Therefore, the physically based model which can consider the process of landslide occurrence was proposed and commonly used. However, the most previous physically based model analyses evaluate and consider the strength characteristics for saturated soil only in the susceptibility analysis. But the strength parameters for unsaturated soil such as matric suction should be considered with the strength parameters for saturated soil since the shear strength in unsaturated soil also plays important role in the stability of slope. Consequently this study suggested the modified physically based slope model which can evaluate strength characteristics for both of saturated and unsaturated soils. In addition, this study evaluated the thickness of saturated part in slope with rainfall intensity and hydraulic characteristics of slope on the basis of physically based model. In order to evaluate the feasibility, the proposed model was applied to practical example in Jinbu area, Gangwon-do, which was experienced large amount of landslides in July 2006. The ROC graph analysis was used to evaluate the validation of the model, and the analysis results were compared with the results of the previous analysis approach.

• Economic and Environmental Geology
• /
• v.48 no.6
• /
• pp.537-543
• /
• 2015

In Korea, the use of world geodetic system(WGS) has been mandated in year 2010. Accordingly, the national geographic information institute(NGIS) provides the digital maps according to the WGS. Nevertheless, most of the digital geological maps are still based on the Tokyo Datum(TD). Therefore, users should conduct 2D/3D geological spatial analysis after converting the coordinates of digital geological maps to WGS. The conversion process is often tedious and troublesome for certain users. Therefore, in this study, the method to transform coordinate from TD to WGS using ArcToolbox is introduced for users not familiar with the process. For a better appreciation, the Chungju and Hwanggang-ri digital sheets of 1:50,000 scale was chosen as an example. Here, Chungju and Hwanggang-ri sheets were defined based on the TD-central origin and TD-east origin, respectively. The two sheets were merged after the transformation of TD-east origin of Hwanggang-ri to the TD-central origin, and eventually transformed to WGS-central origin. The merged map was found to match exactly with the digital map(Daeso 367041). The problem of coordinate determination in previous digital geological maps was solved effectively. The proposed method is believed to be helpful to 2D/3D geological spatial analysis of various geological thematic maps.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.9 no.4
• /
• pp.247-259
• /
• 2007

In this study, we examined the flux of carbon and water using an eco-hydrological model, Regional Hydro-Ecologic Simulation System (RHESSys). Our purposes were to develop a set of parameters optimized for a well-designed experimental watershed (Gwangneung Research Watershed, GN) and then, to test suitability of the parameters for predicting carbon and water fluxes of other watershed with different regimes of climate, topography, and vegetation structure (i.e Gangseonry Watershed in Mt. Jumbong, GS). Field datasets of stream flow, soil water content (SWC), and wood biomass product (WBP) were utilized for model parameterization and validation. After laborious parameterization processes, RHESSys was validated with the field observations from the GN watershed. The parameter set identified at the GN watershed was then applied to the GS watershed in Mt. Jumbong, which resulted in good agreement for SWC but poor predictability for WBP. Our study showed that RHESSys simulated reliable SWC at the GS by adjusting site-specific porosity only. In contrast, vegetation productivity would require more rigorous site-specific parameterization and hence, further study is necessary to identify primary field ecophysiological variables for enhancing model parameterization and application to multiple watersheds.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.5 no.2
• /
• pp.138-149
• /
• 2003

Korean regional network of tower flux sites, KoFlux, has been initiated to better understand $CO_2$, water and energy exchange between ecosystems and the atmosphere, and to contribute to regional, continental, and global observation networks such as FLUXNET and CEOP. Due to heterogeneous surface characteristics, most of KoFlux towers are located in non-ideal sites. In order to quantify carbon and energy exchange and to scale them up from plot scales to a region scale, applications of various methods combining measurement and modeling are needed. In an attempt to infer regional-scale flux, four methods (i.e., tower flux, convective boundary layer (CBL) budget method, MM5 mesoscale model, and NCAR/NCEP reanalysis data) were employed to estimate sensible heat flux representing different surface areas. Our preliminary results showed that (1) sensible heat flux from the tower in Haenam farmland revealed heterogeneous surface characteristics of the site; (2) sensible heat flux from CBL method was sensitive to the estimation of advection; and (3) MM5 mesoscale model produced regional fluxes that were comparable to tower fluxes. In view of the spatial heterogeneity of the site and inherent differences in spatial scale between the methods, however, the spatial representativeness of tower flux need to be quantified based on footprint climatology, geographic information system, and the patch scale analysis of satellite images of the study site.

• The Korean Journal of Quaternary Research
• /
• v.20 no.2
• /
• pp.1-10
• /
• 2006

Flooding hazard caused by natural and artificial environmental changes is closely associated with change in river bed configuration. This study is aimed at explaining a river-bed change related to soil erosion in the Keum river basin using GIS and RS. The USLE was used to compute soil erosion rate on the basis of GIS. River-bed profiles stretching from Kongju to Ippo were measured to construct a 3D-geomorphological map. The river-bed change was also detected by remote sensing images using Landsat TM during the period of 1982 to 2000 for the Keum river. The result shows that USLE indicates a mean soil erosion rate of $1.8\;kg/m^2/year$, and a net increase of a river-bed change at a rate of $+5\;cm/m^2$/year in the Kangkyeong area. The change in river-bed is interpreted to have been caused by soil erosion in the downstream of the Keum river basin. In addition river-bed change mainly occurred on the downstream of the confluence where tributaries and the main channel meet. Other possible river-bed change is caused by a removal of fluvial sand aggregates, which might have resulted in a net decrease of exposed area of sediment distribution between 1991 and 1995, while a construction of underwater structures, including a bridge, a reclamation of sand bars for rice fields and dikes, resulted in an increase of the exposed area of river-bed due to sediment accumulation.

• Journal of the Korean association of regional geographers
• /
• v.22 no.1
• /
• pp.195-210
• /
• 2016

The purpose of this study was to understand characteristics of groups vulnerable to extreme heat and to reduce mortality caused by high temperature. For this purpose, relationship between socioeconomic factors and mortality-threshold temperatures were studied. The study area was limited to Seoul (South Korea) and climate data from 2000 to 2010 was used. Our results indicate that mortality-threshold temperatures for regions with a high proportion of aging population and a low proportion of aging population are $27.6^{\circ}C$ and $27.9^{\circ}C$, respectively. It was also found that a relative size of welfare dependant population did not affect mortality-threshold temperatures. However, regions with a high proportion of aging and welfare dependant population experienced $0.7^{\circ}C$ lower mortality-threshold temperature than other regions. This implies that low income and older people in Seoul are more easily affected by high temperature. Thus, this study suggests that it needs a policy targeted to low income and aging population to decrease mortality rate caused by extreme heat.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.59 no.1
• /
• pp.21-30
• /
• 2017

Soil erosion has been issued in many countries since it causes negative impacts on ecosystem at the receiving water bodies. Therefore best management practices to resolve the problem in a watershed have been developed and implemented. As a prior process, there is a need to define soil erosion level and to identify the area of concern regarding soil erosion so that the practices are effective as they are designed. Universal Soil Loss Equation (USLE) were developed to estimate potential soil erosion and many Geographic Information System (GIS) models employ USLE to estimate soil erosion. Sediment Assessment Tool for Effective Erosion Control (SATEEC) is one of the models, the model provided several opportunities to consider various watershed peculiarities such as breaking of slope length, monthly variation of rainfall, crop growth at agricultural fields, etc. SATEEC is useful to estimate soil erosion, however the model can be implemented with ArcView software that is no longer used or hard to use currently. Therefore SATEEC based on ArcView was rebuild for the ArcGIS software with all modules provided at the previous version. The rebuilt SATEEC, ArcSATEEC, was programmed in ArcPy and works as ArcGIS Toolset and allows considering monthly variations of rainfall and crop growth at any watershed in South-Korea. ArcSATEEC was applied in Daecheong-dam watershed in this study, monthly soil erosion was estimated with monthly rainfall and crop growth variation. Annual soil erosion was computed by summing monthly soil erosion and was compared to the conventional approach to estimate annual soil erosion. The annual soil erosion estimated by the conventional approach and by summing monthly approach did not display much differences, however, ArcSATEEC was capable to provide monthly variation of soil erosion.